The present invention relates to cationic amphiphilic compounds that are useful for intracellular delivery of biologically active molecules such as nucleic acids. Once introduced to the cytoplasm or nucleus of a cell, many biologically active molecules are capable of influencing cell function. For instance, transfection, the process of introducing expressible DNA and mRNA into cells, can lead to expression and secretion of desirable proteins and polypeptides, and can be used for gene therapy. Similarly, delivery of naturally-occurring and synthetic chemical compounds can be used to modify cell properties and function. However, efficient delivery of these compounds to the cell has often proved difficult if not impossible, since the cell membrane presents a selectively permeable barrier. Accordingly there is a need to develop new methods that facilitate entry of biologically active molecules into cells, and in particular, into cells of patients for therapeutic application.